Methods for improving uplink (UL) coverage, throughput and transmission latency are being investigated in Release 6 (R6) of the 3rd Generation Partnership Project (3GPP). In order to successfully implement these methods, the scheduling and assigning of UL radio resources have been moved from a radio network controller (RNC) to a Node-B such that the Node-B can make decisions and manage UL radio resources on a short-term basis more efficiently than the RNC, even if the RNC retains overall control over the Node-B.
In order for the WTRU to transmit on enhanced dedicated channel (E-DCH), the WTRU must identify the need for E-DCH transmissions by transmitting E-DCH channel allocation requests to the Node-B. Then, the Node-B provides allocation of E-DCH physical resources to the WTRU that have requested the E-DCH channel.
When there are not enough UL resources for the E-DCH channel allocation requests, the Node-B cannot immediately allocate resources of E-DCH transmission for all WTRUs that have requested the E-DCH. If the WTRU does not receive an E-DCH allocation within a predetermined time period, the WTRU may retransmit the request until the WTRU receives E-DCH channel allocation information.
Since the transmission of an E-DCH channel allocation request interferes with other WTRUs, when each WTRU transmits and retransmits the same channel allocation request multiple times, the UL EU channel will increase UL interference. Thus, the overall efficiency of the system will be degraded.
Therefore, there is a need to minimize utilization of the UL signaling channel while maintaining proper EU scheduling operation. Furthermore, a procedure for fault-isolating EU transmission failures is desired.